Time division multiplexing (TDM) networks have been used since the 1960's in telecommunications to digitally transmit voice. As such, TDM networks have been developed with a robust suite of tools, e.g., an Operations, Administration, and Management suite, which maintains a level of reliability that telecommunications operators have grown to expect. With the advent of optical networks, telecommunications operators have applied TDM to Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) optical networks.
Over time, the telecommunications industry has experienced increasing economic pressure to integrate different services, e.g., by adding packet based services to TDM services. As demand for packet based services increases, e.g., Ethernet, there is a demand for convergence of the various services, such as, packet-over-TDM and TDM-over-Ethernet. However, packet based networks do not have the robust management tools available to TDM networks. Furthermore, integrating two or more types of networks and/or services require protocol convergence layers and common framing layers that add complexity to transporting the underlying data over the transport network.